The male silkworm moth has a sense of smell so acute that it can detect a single molecule of female moth pheromone from nearly 2 km away. This makes it the champion 'smeller' in the animal kingdom. But in second place, with her own specialised olfactory sensitivity must surely come the now legendary Joy Milne, a retired nurse from Perth (Scotland not Australia!).

You will have read her story, I'm sure. Joy has what is, by any standards, a remarkable sense of smell. She is able to detect a range of complex odours to a standard that would embarrass most professional sommeliers. It runs in the family – her grandmother was the same. But most remarkable of all is not her capacity to distinguish a 1961 Chateau Lafite from a 1959. It is her astonishing ability to identify people with Parkinson's from their smell.

Joy can tell if you have Parkinson's or not. And she can do this with astonishing accuracy. But that's not all - she can also detect people in the prodromal phase – that is those not yet diagnosed with Parkinson's. In other words, she could potentially tell if you are going to get Parkinson's. You have to be impressed. This, after all, is the holy Grail in terms of Parkinson's and neuroprotection. Early detection is the incentive to develop neuroprotective agents. And the development of neuroprotectants is the incentive for early detection. Joy Milne, with her astonishing olfactory powers, provides that link.

She first became aware of this gift with her husband, Les. Over the course of several years she noticed his scent changed, leading up to the point where he was diagnosed with Parkinson's. When she attended local Parkinson's UK meetings in Edinburgh, she noticed that this distinctive smell was common to all people with Parkinson's. One thing led to another and, in 2012, she found herself talking to Tilo Kunath, at Edinburgh University who was keen to investigate further. Along with Perdita Barran, then in Edinburgh but subsequently in Manchester, the teams identified a number of volatile organic molecules associated with the Parkinson's 'scent', in essence its biochemical fingerprint. In February 2016, an editorial in the Lancet summarised the story to that point [1].

While the labs worked on the biochemistry, Joy continued to meet people with Parkinson's, keen to hear her story and share their own. One such encounter occurred in 2016, with Alison Williams a self-confessed "late-onset academic", based in Edinburgh and interested in ways of alleviating Parkinson's symptoms.  Although the two hit it off instantly, they didn't meet again until the following year and when they next met, late in 2017, Joy was struck by how much less Alison smelled!

Now if it was you or I, we might make a comment to that effect. But Joy, now officially "honorary lecturer in analytical olfaction" in Manchester, could not do so. Her nose, now essentially a research instrument, was, in one sense "owned" by the University and governed by ethical committee constraints on disclosure. But so substantial was the change she had detected in Alison – and so unexpected – that Joy quickly sought and obtained approval to tell Alison. "Whatever you're doing, keep on doing it" she said.

Alison went back over old diaries looking for clues. It soon turned out that  the "whatever you're doing" was exercise, still the only freely available treatment for Parkinson's and certainly the only one widely accepted to be neuroprotective.

All well and good but Alison is not the ten-minutes-on-the-exercise-bike-should-just-about-do-it type. She focused not on exercise generally but upon those programs with a distinct cognitive dimension. She originally started with Tai Chi, before adding Pilates, Dance for Parkinson's, and the magnificently named "Mature Latin Movers". That's not all. Alison now does Tai Chi with weapons and, most recently, Taiko drumming!

Has it benefited her? Well, the simple answer is yes. Nobody in her MLM or Taiko class knows that she has Parkinson's. And when I spoke to her recently by Skype, I was hard pressed to spot symptoms despite the fact she has been diagnosed more than seven years ago.

Alison's daily diary revealed what exercise she was undertaking, how much, how complex and how intensive (physically and cognitively) it was. Over the timeframe between the first and second time she met Joy, she noticed improvements in several motor and non-motor symptoms. Her sense of smell improved, along with gait, coordination and much else. What type of exercise is responsible? Alison's money is on the MLM class! And who would argue.

Joy also had the opportunity to smell Alison over this time period, confirming that the symptom benefits were matched by improvements in smell.

It wasn't long before they were thinking in terms of disseminating their results. The data was exciting – it needed somewhere where a poster would have a big impact. A big international meeting for instance, with a mix of patients, scientists and clinicians. And they settled on…... drum roll please….. WPC 2019 in Japan!

A big adventure – unfurling the poster [2] onto the board in Kyoto. And boy did it make an impression. At times you could not get near their poster at the meeting. It was like the first day of the Harrods sale! It felt as though everybody wanted to ask questions. Could this be a tool for assessing progression of Parkinson's? Or even the lack of progression? Some answers, many more questions, much input. All helpful.

So where do they go next? Joy and Alison have thought of that – a much more detailed study of whether exercise and subjective self-assessment of motor symptoms correlates with objective changes in smell. A win-win situation – good science and the embodiment of patient empowerment.

Were they happy they attended the WPC meeting? Absolutely. When I spoke to her, Alison was quick to point out how much she had learnt about ways of assessing her own illness from the insights of Tim Hague, Sara Riggare and others. "It's given me fantastic conversations, some very clear practical tools and terrific inspiration seeing how other people get on with it (Parkinson's)".

Yup, that's WPC.

1. Morgan J. Joy of super smeller: sebum clues for PD diagnostics. (2016) Lancet neurology 15, 138-9.

2. Williams A & Milne J. Parkinson's smell levels, symptom management and empowerment: when Joy met Alison. Poster at WPC Kyoto, June 2019.